Fig. 8. Model for the affects of LIF and BMP on astrocyte differentiation. Stem cells in the developing rodent brain are initially GFAP^-, but later express GFAP during the postnatal and adult periods. LIF fosters maintenance of stem/progenitor trait throughout the continuum, but converts GFAP^- cells into GFAP⁺ ones. By contrast, BMPs induce exit from cell cycle and the loss of stem/progenitor cell traits, resulting in what we have termed a mature astrocyte. Inhibition of endogenous BMPs is required to prevent maturation of adult stem cells into the mature astrocytic phenotype.